Field of the Invention
The present invention relates to an organic compound and an organic light emitting device including the same, and more particularly, to an organic compound capable of improving the efficiency of light emission and lowering the driving voltage of an organic light emitting device, and to an organic light emitting device including the same.
Description of the Related Art
An image display device that implements a variety of information on a screen pertains to a core technology at the information and communication age, and is progressing in the direction of being thinner, lighter, easy to carry, and high functional. In recent years, with the development of the information society and the increase in various types of demands for display devices, studies on flat panel display devices, such as liquid crystal display (LCD), plasma display panel (PDP), electro luminescent display (ELD), field emission display (FED), and organic light emitting diode (OLED) are being actively conducted.
Of these, the organic light emitting diode is a device that, when charges are injected into an organic light emitting layer disposed between an anode and a cathode, electrons and holes make pairs, and then the pairs are extinguished to emit light. The organic light emitting device can be manufactured on a flexible transparent substrate such as plastic, driven at a lower driving voltage than a plasma display panel or an inorganic electroluminescent (EL) display, consume less power, and have excellent colors. In particular, an organic light emitting device implementing a white color is used for several purposes, such as an illumination, a thin type light source, a backlight of a liquid display device, or a full color display device employing a full color filter.
In the development of the white organic light emitting device, high efficiency, long lifetime, color purity, color stability with current and voltage changes, easy manufacturing of devices, and the like are important, and thus research and development according to each type are being conducted. There are several types in the structure of the white organic light emitting device, which can be largely classified into a single-layer light emission structure and a multi-layer light emission structure. Of these, a multi-layer light emission structure in which a fluorescent blue light emitting layer and a phosphorescent yellow light emitting layer are stacked (tandem) is mainly being adopted for a long-lifetime white color display device.
Specifically, a phosphorus stack structure in which a first stack using a blue fluorescent device as a light emitting layer and a second stack using a yellow-green phosphorus device as a light emitting layer are stacked is being used. This white organic light emitting device displays a white light by a mixture effect of a blue light emitted from a blue fluorescent device and a yellow light emitted from a yellow phosphorescent device. In this instance, a charge generation layer which doubles the efficiency of current generated from a light emitting layer and facilitates the distribution of charges is provided between a first stack and a second stack. The charge generation layer, which generates charges including electrons and holes, doubles the efficiency of current generated from the light emitting layer and facilitates the distribution charges, thereby preventing the driving voltage from being raised.
In addition, aromatic diamine derivatives have been well known as a hole transport material provided in the organic light emitting device. In the organic light emitting devices using the aromatic diamine derivatives as a hole transport material, the applied voltage is increased to obtain a sufficient light emission brightness, causing a decrease in the device lifetime and an increase in power consumption. For solving these problems, proposed is a method of doping a hole injection layer with an electron-acceptor compound, such as Lewis acid, or forming a separate layer. However, the electron-acceptor compound used therein is unstable in the handling in the manufacturing procedure of the organic light emitting device or is deficient in stability of, such as heat resistance, at the time of driving, and causes a decrease in the lifetime. In addition, F4TCNQ (tetrafluoro tetracyanoquinodimethane), which is a representative electron-acceptor compound, has a small molecular weight and contains a fluorine substituent, and thus has high sublimation property and is diffused in the apparatus at the time of vacuum deposition, causing fears that pollutes the apparatus or device. HAT-CN, which is another representative compound, has problems in that the deposition thickness is limited due to crystallization and the current leaks.
In particular, the electrodes are generally formed of a metal material or a metal oxide, and thus, in the instance where the interface between the inorganic material and an organic material used as a charge injection material is not stable, the performance of the device can be remarkably degraded due to the heat applied from the outside, the heat generated from the inside, or an electric field applied to the device. Therefore, the development of a material that forms a stable interface with the electrode, has a high charge transport capability, and has a predetermined molecular weight or more is required.